1. Field of Invention
This invention generally relates to an intravenous fluid delivery system. More particularly, this invention relates to a drip chamber that minimizes the formation of air bubbles in an intravenous fluid delivery system by limiting the flow rate of the intravenous flow through the chamber.
2. Description of Related Art
Intravenous fluid delivery systems are used by medical personnel to provide nutrients and/or medication to a patient via a vein in the patient's arm. Such systems are used during surgery or when a patient is otherwise unable to ingest nutrients or medication orally.
An intravenous fluid delivery system generally includes a bag or container of intravenous fluid that is connected through a series of conduits to a needle inserted into a vein in the patient. The bag or container is supported at a higher elevation than the patient so that intravenous fluid flows through the conduits by the force of gravity.
A drip chamber is disposed in the conduit arrangement between the intravenous fluid bag and the needle to allow medical personnel to visually inspect the "drip", i.e., flow rate, of intravenous fluid through the system. From the drip rate, the flow rate of the infused fluid can be calculated. One or more valves are disposed within the system to control the intravenous fluid flow rate. Typically, there is at least one valve between the drip chamber and the needle. The drip chamber also provides a pocket for the collection of air in the system.
In particular, the drip chamber is constructed of a clear material and has a top inlet port connected to the conduit(s) leading to the intravenous fluid bag and a bottom outlet port connected to the conduit(s) leading to the needle. The inlet and outlet ports enclose opposite ends of a generally-cylindrical column, and fluid drips from the inlet downwardly through the column where it collects at the bottom of the column and exists via the outlet.
When infusing fluids intravenously, particularly under pressurized conditions, such as priming the chamber, the infused fluid flows at a high velocity from the drip chamber inlet opening into a pool of fluid contained in the bottom of the drip chamber. As the high velocity fluid impinges the pool surface, bubbles are entrapped in the fluid pool, thus causing an air-bubble mixture to form. Furthermore, to infuse the fluids intravenously, the valve between the drip chamber and needle is opened to permit the fluid in the drip chamber to flow from the chamber outlet opening to the conduit(s) reading to the needle.
When the valve between the drip chamber and needle is opened, the negative pressure within the intravenous fluid delivery system causes any fluid present in the chamber to vacate the chamber very rapidly. Additionally, the negative pressure causes the fluid entering the drip chamber from the conduit(s) leading from the intravenous fluid bag to also pass very rapidly through the drip chamber. The rapid flow of the intravenous fluid through the chamber and out the outlet opening may result in formation of an air-bubble mixture in the fluid flowing toward the patient. This requires a time-consuming effort to purge the air bubbles from the conduits leading to the patient. If air bubbles are not purged, they may enter the patient and cause an embolism or other harmful effects.